// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_WINDOW_DELEGATE_H_
#define CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_WINDOW_DELEGATE_H_

#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "content/browser/renderer_host/overscroll_controller.h"
#include "content/browser/web_contents/aura/overscroll_navigation_overlay.h"
#include "content/browser/web_contents/web_contents_impl.h"
#include "ui/aura_extra/image_window_delegate.h"

namespace content {

// The window delegate for the overscroll window. This processes UI trackpad and
// touch events and converts them to overscroll event. The delegate destroys
// itself when the window is destroyed.
class CONTENT_EXPORT OverscrollWindowDelegate
    : public aura_extra::ImageWindowDelegate {
public:
    OverscrollWindowDelegate(OverscrollControllerDelegate* delegate,
        const gfx::Image& image);

private:
    FRIEND_TEST_ALL_PREFIXES(OverscrollWindowDelegateTest, BasicOverscrollModes);

    ~OverscrollWindowDelegate() override;

    // Starts the overscroll gesture.
    void StartOverscroll();

    // Resets the overscroll state.
    void ResetOverscroll();

    // Completes or resets the overscroll from the current state.
    void CompleteOrResetOverscroll();

    // Updates the current horizontal overscroll.
    void UpdateOverscroll(float delta_x);

    // Overridden from ui::EventHandler.
    void OnKeyEvent(ui::KeyEvent* event) override;
    void OnMouseEvent(ui::MouseEvent* event) override;
    void OnScrollEvent(ui::ScrollEvent* event) override;
    void OnGestureEvent(ui::GestureEvent* event) override;

    // Delegate to which we forward overscroll events.
    OverscrollControllerDelegate* delegate_;

    // The current overscroll mode.
    OverscrollMode overscroll_mode_;

    // The latest delta_x scroll update.
    float delta_x_;

    // The ratio of overscroll at which we consider the overscroll completed.
    const float complete_threshold_ratio_;

    // The threshold for starting the overscroll gesture, for touchscreen or
    // touchpads.
    const float start_threshold_touchscreen_;
    const float start_threshold_touchpad_;

    // The threshold for starting the overscroll gesture for the current touch
    // input.
    float active_start_threshold_;

    DISALLOW_COPY_AND_ASSIGN(OverscrollWindowDelegate);
};

} // namespace content

#endif // CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_WINDOW_DELEGATE_H_
